Recently, an increase in the recording density of magnetic discs has accelerated and presently, hard disc drive devices (HDD) which have a capacity on an order of several hundreds gigabytes have become mainstream. Due to the increases in the recording density in magnetic discs, a floating amount of each magnetic disc lowers.
In a recent magnetic head assembly, at the top of a suspension spring of about 15 mm˜20 mm, a slider having a size of about 0.3 mm˜1 mm square is attached and a gap between a thin film magnetic head and a disc becomes a distance of a few nm to 10 nm.
A magnetic disc as an information recording medium and a magnetic head (magnetic head assembly) performing data reading and writing in the magnetic disc for an HDD in such relationship are subjected to a precise performance inspection with respective inspection devices at the production stages thereof.
Further, present uses of HDDs are spreading in the fields such as automotive products, home appliances and audio products, and hard disc drive devices of from 3.5 inches to 1.8 inches and even less than 1.0 inch are built into a variety of products and used therein. Therefore, price reduction and mass production of the HDDs are demanded. For this reason, a magnetic head inspection device having a reduced size, which can inspect many magnetic heads efficiently is needed.
In order to enhance an inspection efficiency of magnetic discs or magnetic heads, an inspection device in which a plurality of inspection decks are provided and signals from magnetic heads are distributed or selectively changed over between the inspection decks and processed therein respectively is disclosed and already known from JP-A-2001-52319 and JP-A-2006-179107.
An inspection deck in a conventional magnetic head inspection device is constituted in such a manner that one or two carriages are provided for one spindle and normally one corresponding measurement unit is provided for the respective carriages. After completing inspection of a magnetic head in a unit of magnetic head assembly, the post-inspection magnetic head assembly is exchanged with a new pre-inspection magnetic head assembly serving as an inspection object. The exchange in this instance is presently performed manually. The same is true with respect to an inspection device of magnetic discs.
Therefore, in order to enhance a throughput of the magnetic head inspection, the present assignee proposed a system of automatically inspecting magnetic head assemblies in which the magnetic head assembly exchange work is automated and many magnetic head assemblies are accommodated in a tray and are fed therefrom, and filed as Japanese Patent Application No. 2007-172300. This system is for automating the inspection system from the tray to magnetic head assemblies. However, in this instance, when feeding and discharging of trays are delayed in time, of the throughput of magnetic head inspection is unable to be enhanced.
One of ideas of continuous feeding and discharging system of trays themselves is to dispose the trays themselves in double and to use one of the trays for inspection and during the use thereof to exchange another tray emptied after completing the parts inspection with a feed tray and to discharge the same. Further, a tray for accommodating post-inspection parts is also necessary. When the tray is filled with post-inspection parts, the tray has to be discharged and an empty tray has to be fed.
When such a tray feeding and discharging system is employed, respective two systems are necessitated for feed trays of pre-inspection electronic parts (for example, the above magnetic head assemblies) and for discharge trays of post-inspection electronic parts. Moreover, empty trays are respectively generated in different timings and are necessitated for respective systems.
Moreover, good (GD) trays in which electronic parts passed the inspection are accommodated are frequently provided for respective ranks classified according to the inspection result. In such instance, a frequency of timing control for tray feeding and discharging and a frequency of tray exchanging extremely increase. Thereby, the work efficiency for the tray feeding and tray discharging is degraded. Further, since a system for feeding and discharging of many trays is needed, a problem arises of increasing the size of the device.